Vayu Education of India - Kopykitab

Er. Shobhit SharmaB.E. M.Tech

Dean AcademicDelhi Institute of Engineering & Technology

Meerut

Design of Concrete Structure-I

AN ISO 9001:2008 CertIfIed COmpANy

Vayu Education of India2/25, Ansari Road, Darya Ganj, New Delhi-110 002

Design of Concrete Structure-I

Copyright © Vayu Education of India

ISBN: 978-93-82174-50-9

First Edition: 2013

Rs. 200/-

All rights reserved. No part of this publication may be reproduced, stored in a re-trieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior permission of the Authors.

Published by:

AN ISO 9001:2008 CertIfIed COmpANyVAYU EDUCATION OF INDIA2/25, Ansari Road, Darya Ganj, New Delhi-110 002Ph.: 91-11-43526600, 41564445Fax: 91-11-41564440E-mail: [email protected], [email protected]: www.veiindia.com

Dedicated toMy

Guru Ji

Preface

The book Design of Concrete Structure-I is the text deals with indeterminate structure. The book covers the syllabus of ‘Design of Concrete Structure-I of IIIrd year civil Engineering students of Mahamaya Technical University and other Indian Universities.

Author thanks all their friends & colleagues and family members who helped in writing this text. Author is also grateful to the secretary and chairman of D.I.E.T., Meerut, for their co-operation during the writing of text. Finally author also thanks the team of Vayu Education of India for their sincere efforts especially Dr. R.K. Jain, for publishing this book.

—Er. Shobhit Sharma

Syllabus

UNIT – 1Concrete Making materials , mix design , Properties of concrete and reinforcements,

testing of concrete , Introduction to Various Design Philosophies, Design of Rectangular Singly and Doubly Reinforced Sections by Working Stress Method. 8

UNIT – 2Assumptions in Limit State Design Method, Design of Rectangular Singly and

Doubly Reinforced beams, T-beams, L-beams by Limit State Design Method. 8

UNIT – 3Behaviour of RC beam in Shear, Shear Strength of beams with and without shear

reinforcement, Minimum and Maximum shear reinforcement, design of beam in shear, Introduction to development length, Anchorage bond, flexural bond. (Detailed Examples by Limit State Design Method), Failure of beam under shear, Concept of Equivalent Shear and Moments.

UNIT – 4Design of one way and two way solid slabs by Limit State Design Method,

Serviceability Limit States, Control of deflection, cracking and vibrations. 8

UNIT – 5Design of Columns by Limit State Design Method- Effective height of columns,Assumptions, Minimum eccentricity, Short column under axial compression,

equirements for reinforcement, Column with helical reinforcement, Short column under axial load and uni-axial bending, Design of columns under bi-axial loading by Design.

Contents

Preface ....................................................................................................(iiv)

UNIT -I1. DESIGN OF CONCrETE STrUCTUrE-I ......................................1 1.1 Concrete Materials ......................................................................................3 1.2 Reinforced Concrete Properties ..................................................................4 1.3 Concrete Mix Design ..................................................................................9 1.4 Various Design Principles .........................................................................10 1.5 Reinforced Concrete Design Philosophies ................................................10 1.6 Multiple Safety Factors .............................................................................15 1.7 Tests For Workability of Concrete ............................................................16 1.8 Test Strength of Sample ............................................................................22 1.9 Strength of Concrete ..................................................................................22 1.10 Permissible Stresses In Concrete (I.s. 456 - 2000) ....................................23 1.11 Modular Ratio M .......................................................................................24 1.12 Permissible Shear Stress In Concrete ........................................................24 Review Questions ......................................................................................25

2. WOrkING STrESS DESIGN METhOD .......................................26 1.1 Introduction ...............................................................................................26 1.2 Rectanglular Beams Reinforced In Tension (Singly Reinforced Beam) ...28 1.3 Design of Rectangular Beams ...................................................................35 1.4 Rectangular Beams Reinforced In Tension And Compression (Doubly

Reinforced Section) ...................................................................................39

Design of Concrete Structure-I12

UNIT-II2. LIMIT STATE–DESIGN...................................................................53 2.1 Introducstion ..............................................................................................53 2.2 Assumptions For Limit State Analysis ......................................................53 2.2 Analysis of Singly Reinforced Rectangular Sections ...............................56 2.3 Analysis And Design of Rectangular Beams ............................................63 2.4 Analysis of Rectangular Beams ................................................................63 2.5 Design of Rectangular Beams ...................................................................64 2.6 Beams Reinforced In Tension And Compression ......................................68 2.7 Types of Problems .....................................................................................70 2.8 Analysis of The Flanged Beam Section ....................................................77 2.9 Analysis of Flanged Section With Tension Einforcement .........................78 2.10 Design of The Flanged Beam Section Flanged Beam With Tension Rein-

forcement ...................................................................................................86

UNIT-III LIMIT STATE OF COLLApSE IN ShEAr .................................101 3.1 Introduction .............................................................................................101 3.2 Types of Shear Failures ...........................................................................101 3.3 Calculation of Shear Stress .....................................................................102 3.4 Design Shear Strength In Concrete Beams .............................................103 3.5 Tpyes of Shear Reinforcements ..............................................................106 3.6 Design of Links (Stirrups) .......................................................................107 3.7 Rules For Minimum Shear Reinforcement .............................................109 3.8 Step-by-step Procedure For Design of Links ..........................................113 3.9 Design of Bent-up Bars As Shear Reinforcements .................................114 3.10 Enhanced Shear Near Supports–Critical Section For Shear ...................116 3.11 Shear In Slabs ..........................................................................................117 3.12 Detailing of Steel .....................................................................................117 3.13 Shear In Members Subjected To Compression And Bending .................117 3.14 Shear In Beams of Varying Depth ...........................................................118 3.15 Detailing of Vertical Stirrups In Beams .................................................119 Questions .................................................................................................129 Problems ..................................................................................................129

Contents 13

BOND, ANChOrAGE, DEVELOpMENT LENGThS AND SpLICING ..............................................................................132 3.1 Introduction .............................................................................................132 3.2 Local (Or Flexural) Bond ........................................................................133 3.3 Average (Anchorage) Bond Stress ..........................................................134 3.4 Development Length ...............................................................................135 3.5 End Anchorage of Bars ...........................................................................136 3.6 Checking Development Lengths of Tension Bars ...................................136 3.7 Conditions For Termination of Tension Reinforcement ..........................139 3.8 Development Length of Compression Bars ............................................139 3.9 Equivalent Development Length of Hooks And Bends ..........................139 3.10 Anchorage of A Group of Bars (Bundled Bars) .....................................140 3.11 Splicing of Bars .......................................................................................141 3.12 Lap Splices ..............................................................................................142 3.13 Curtailment of Bars And Their Anchorage ..............................................144 3.14 Importance of Laps And Anchorage Length ...........................................145 Questions .................................................................................................148 Problems ..................................................................................................148

UNIT-IV DESIGN OF SLABS ........................................................................155 4.1 Thickness of A Slab .................................................................................155 4.2 Loads On Slabs ........................................................................................157 4.3 Imposed Loads (Live Loads) ...................................................................158 4.4 Steps To Be Followed In The Design of A One Way Slab ......................158 4.5 Slab Carrying Concentrated Load ...........................................................177 4.6 Two Way Slabs (Slabs Spanning In Two Directions) ..............................187 4.7 Rankine-grashoff Theory.........................................................................188 4.8 Two Way Slabs With Corners Held Down (Marcus Correction) ............190 4.9 Asnalysis of Two-way Slabs By I.s. Code ..............................................194

UNIT-V COLUMNS AND WALLS ...............................................................227 5.1 Introduction .............................................................................................227 5.2 Braced And Unbraced Columns ..............................................................228

Design of Concrete Structure-I14

5.3 Unsupported And Effective Length (Height) of Columns ......................229 5.4 Slenderness Limits For Columns ............................................................230 5.5 Derivation of Design Formula For Short Columns .................................230 5.6 Checking Accidental Eccentricity ...........................................................232 5.7 Requirement of Longitudinal Steel (Step No - 4) ...................................233 5.8 Requirement of Lateral Ties (Links) (Step No – 5) ................................233 5.9 Procedure For Design of Short Column Under Axial Compression .......234 5.10 Strength of Helically Reinforced Short Column .....................................236 5.11 Calculation of Spacing of Spirals ............................................................237 5.12 Placement of Steel In Circular Columns .................................................239 5.13 Comparison of Tied And Spirally Reinforced Columns .........................239 5.14 Design of Non-rectangular Columns .......................................................239 5.15 Detailing of Columns ..............................................................................240 Review Questions ....................................................................................247 Problems ..................................................................................................247 5.16 Design of Short Columns With Moments ...............................................249 5.17 Methods of Design ..................................................................................250 5.18 Uniaxial Bending (Design Assumptions) ................................................250 5.19 Stress-strain Curve For Steel ...................................................................251 5.20 Column Interaction Diagram ...................................................................252 5.21 Use of Equilibrium Equations To Construct The Interaction Diagram For

Rectangular Sections ...............................................................................254 5.22 Interaction Curves In Sp 16 .....................................................................257 5.23 Interaction Diagram For P = 0 .................................................................257 5.24 Shape of Interaction Curves ....................................................................259 5.25 Accidental Eccentricity In Columns .......................................................259 5.26 Use of Interaction Diagrams For Design And Analysis (Method 1) .......259 5.27 Design of Eccentric Columns By Equilibrium Equation (Method 2) .....260 5.28 Simplified Method (Method 3) ................................................................261 5.29 Member Subjected To Biaxial Bending ..................................................262 5.30 Simplified Bs 8110 Method For Biaxial Bending ...................................264 5.31 Shear In Columns Subjected To Moments ............................................265 5.32 Representation of Column Design Charts ...............................................266 Review Questions ....................................................................................280 Problems ..................................................................................................280 5.33 Effective Length of Columns ..................................................................281 5.34 Table of Coefficients ...............................................................................282

Contents 15

5.35 Wood’s Charts For Columns In Building Frames ...................................286 5.36 Modification For Beam Stiffness ............................................................288 5.37 Aci Charts ................................................................................................289 5.38 Use of Formulae For Columns In Building Frames ................................289 5.39 Ac For Specific Conditions As Given In Bs ............................................289 Review Questions ....................................................................................296 Problems ..................................................................................................296

Annexture ................................................................................................301 Index ........................................................................................................315

Unit I

• Design of Concrete Structure-I• Working Stress Design Method

Design of Concrete Structure I By Er.Shobhit Sharma

Publisher : Vayu Education ISBN : 9789382174509 Author : Er. ShobhitSharma

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